Add call size bm_diff
diff --git a/grpc.gyp b/grpc.gyp
index 487d529..e61166e 100644
--- a/grpc.gyp
+++ b/grpc.gyp
@@ -2316,6 +2316,7 @@
         'third_party/benchmark/src/commandlineflags.cc',
         'third_party/benchmark/src/complexity.cc',
         'third_party/benchmark/src/console_reporter.cc',
+        'third_party/benchmark/src/counter.cc',
         'third_party/benchmark/src/csv_reporter.cc',
         'third_party/benchmark/src/json_reporter.cc',
         'third_party/benchmark/src/reporter.cc',